Oviduct secretions provide the environment for sperm capacitation, fertilization, and early embryonic development. Further, these functions appear to be hormonally controlled. Therefore a comprehensive knowledge of the composition of oviduct fluid and hormonally induced changes it undergoes may yield insight into these processes. This application proposes to examine the biological characteristics and to purify an inhibitor of embryo development occurring naturally in the oviduct during estrogen domination. The steroid concentrations in the oviduct during estrus and pseudopregnancy will also be examined. Finally, isolation and characterization of sulfated, oviduct specific macromolecules will be carried out, and efforts will be made to substantiate that these components are likely the products of the prominent secretory granules of the oviduct epithelium. These macromolecules may play an important role in one of the above mentioned processes. It is envisioned that such information may provide the basis of new methods of birth control.